Three-dimensional printed dental appliances using support structures

ABSTRACT

Systems and methods are disclosed for fabricating a dental or oral appliance utilizing support structures. A three dimensional representation of the dentition of a patient may be captured and reconfigured for correcting one or more malocclusions. The oral appliance may be printed upon an inner structure which supports the oral appliance during fabrication. The inner structure may be subsequently removed once the oral appliance is completed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/230,216 filed Aug. 5, 2016, which claims the benefit of priority toU.S. Prov. App. No. 62/238,514 filed Oct. 7, 2015, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for creatingorthodontics. More particularly, the present invention relates tomethods and apparatus for fabricating one or more oral appliances formedvia three-dimensional printing methods upon a corresponding supportstructure which is removable from the oral appliance after the oralappliance has been fabricated.

BACKGROUND OF THE INVENTION

Orthodontics is a specialty of dentistry that is concerned with thestudy and treatment of malocclusion, which can be a result of toothirregularity, disproportionate facial skeleton relationship, or both.Orthodontics treats malocclusion through the displacement of teeth viabony remodeling and control and modification of facial growth.

This process has been traditionally accomplished by using staticmechanical force to induce bone remodeling, thereby enabling teeth tomove. In this approach, braces consisting of an archwire interfaces withbrackets that are affixed to each tooth. As the teeth respond to thepressure applied via the archwire by shifting their positions, the wiresare again tightened to apply additional pressure. This widely acceptedapproach to treating malocclusion takes about twenty four months onaverage to complete, and is used to treat a number of differentclassifications of clinical malocclusion. Treatment with braces iscomplicated by the fact that it is uncomfortable and/or painful forpatients, and the orthodontic appliances are perceived as unaesthetic,all of which creates considerable resistance to use. Further, thetreatment time cannot be shortened by increasing the force, because toohigh a force results in root resorption, as well as being more painful.The average treatment time of 24-months is very long, and furtherreduces usage. In fact, some estimates provide that less than half ofthe patients who could benefit from such treatment elect to pursueorthodontics.

Kesling introduced the tooth positioning appliance in 1945 as a methodof refining the final stage of orthodontic finishing after removal ofthe braces (debanding). The positioner was a one-piece pliable rubberappliance fabricated on the idealized wax set-ups for patients whosebasic treatment was complete. Kesling also predicted that certain majortooth movements could also be accomplished with a series of positionersfabricated from sequential tooth movements on the set-up as thetreatment progressed. However, this idea did not become practical untilthe advent of 3D scanning and computer and used by Align Technologiesand others such as OrthoClear, ClearAligner and ClearCorrect to providegreatly improved aesthetics since the devices are transparent.

SUMMARY OF THE INVENTION

In one aspect, systems and methods are disclosed for fabricating one ormore oral appliances by capturing a three dimensional representation ofa body part of a subject such as the dentition and creating a removableinner support structure. One or more of the oral appliances may befabricated directly upon one or more corresponding support structures.Once the oral appliance has been completed, the inner support structuremay be removed to leave the dental appliance that fits over one or moreteeth for correcting malocclusions in the dentition.

One method for fabricating an oral appliance may generally comprisecapturing a three dimensional representation of a dentition of asubject, fabricating a support structure which corresponds to an outersurface of the dentition, forming one or more oral appliances upon anexterior surface of the support structure such that an interior of theone or more oral appliances conform to the dentition, and removing thesupport structure from the interior of the one or more oral appliances.

The one or more oral appliances may be formed in a sequence configuredto move one or more teeth of the subject to correct for malocclusions.Moreover, the support structure may be fabricated from a first materialand the one or more oral appliances may be fabricated from a secondmaterial different from the first material.

Generally, the oral appliance assembly may comprise the supportstructure having an exterior surface which corresponds to an outersurface of the dentition of the subject, wherein the support structureis fabricated from a first material, and the oral appliance formed uponthe exterior surface of the support structure via three dimensionalprinting such that an interior of the formed oral appliance conforms tothe dentition of the subject, wherein the oral appliance is fabricatedfrom a second material different from the first material.

The support structure is generally removable from the interior of theformed oral appliance such that the oral appliance is positionable uponthe dentition. Furthermore, a plurality of oral appliances may be formedwhere each oral appliance is formed in a sequence configured to move oneor more teeth of the subject to correct for malocclusions. Accordingly,each oral appliance may be formed upon a plurality of correspondingsupport structures.

The structures according to the present invention can have a differentstiffness in different parts of the structure and can be madetransparent, even though they are made at least partially via additivemanufacturing. The free-form structures according to the presentinvention can further be made as a single part, and may further compriseinternal or external sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description of the figures of specific embodiments of theinvention is merely exemplary in nature and is not intended to limit thepresent teachings, their application or uses. Throughout the drawings,corresponding reference numerals indicate like or corresponding partsand features.

FIG. 1 shows an exemplary 3D printed dental structure with a supportpositioned within the structure.

FIGS. 2A and 2B show different embodiment of a 3D printed dentalstructure having an inner and outer layer.

FIG. 3 shows another embodiment of a 3D printed dental structure with apocket defined within.

FIG. 4 shows yet another embodiment with a ball like material positionedbetween two tooth portions.

FIG. 5 shows an exemplary model having a slot for supporting metal wirestherein.

FIG. 6 shows an exemplary process for adjusting the thickness of the 3Dprinted oral appliance.

FIG. 7 shows an exemplary process for determining the thickness of anoral appliance based on physical simulation.

FIG. 8A shows a perspective view of an example of a basic structureformed into a bottom half and a top half for a dental applianceutilizing a lattice structure which may be used in a 3D printingprocess.

FIG. 8B shows a detail exemplary view of the openings in a latticestructure.

FIG. 8C shows an exemplary end view of a lattice structure havingseveral reticulated layers.

FIG. 8D shows an exemplary end view of a lattice structure havingregions comprised only of the coating material.

FIG. 8E shows a detail perspective view of a lattice structure andcoating having a feature such as an extension formed from the surface.

FIG. 8F shows a detail perspective view of a lattice structure andcoating having different regions with varying unit cell geometries.

FIG. 8G shows a detail perspective view of a lattice structure andcoating having different regions formed with different thicknesses.

FIG. 8H shows an exemplary end view of a lattice structure havingregions with a coating on a single side.

FIG. 8I shows a perspective view of an aligner having at least oneadditional component integrated.

FIG. 8J shows an exemplary end view of a lattice structure a hinge orother movable mechanism integrated along the lattice.

FIG. 8K shows a perspective view of an aligner having one or more(internal) channels integrated.

FIG. 9 shows a perspective detail view of a portion of an aligner havingan area that is machined to have a relatively thicker material portionto accept an elastic.

FIGS. 10A and 10B illustrate a variation of a free-form dental appliancestructure having a relatively rigid lattice structure and one or morefeatures for use as a dental appliance or retainer.

FIG. 10C shows a partial cross-sectional view of a suction featurefabricated to adhere to one or more particular teeth.

FIG. 10D shows a perspective view of a portion of the aligner havingregions configured to facilitate eating or talking by the patient.

FIG. 10E shows a perspective view of a portion of the aligner havingdifferent portions fabricated to have different areas of varyingfriction.

FIG. 10F shows a perspective view of a portion of the aligner having aparticulate coating.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described with respect to particularembodiments but the invention is not limited thereto but only by theclaims. Any reference signs in the claims shall not be construed aslimiting the scope thereof.

As used herein, the singular forms “a”, “an”, and “the” include bothsingular and plural referents unless the context clearly dictatesotherwise.

The terms “comprising”, “comprises” and “comprised of” as used hereinare synonymous with “including”, “includes” or “containing”, “contains”,and are inclusive or open-ended and do not exclude additional,non-recited members, elements or method steps. The terms “comprising”,“comprises” and “comprised of” when referring to recited members,elements or method steps also include embodiments which “consist of”said recited members, elements or method steps.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order, unless specified. It is to be understood that theterms so used are interchangeable under appropriate circumstances andthat the embodiments of the invention described herein are capable ofoperation in other sequences than described or illustrated herein.

The term “about” as used herein when referring to a measurable valuesuch as a parameter, an amount, a temporal duration, and the like, ismeant to encompass variations of +/−10% or less, preferably +/−5% orless, more preferably +/−1% or less, and still more preferably +/−0.1%or less of and from the specified value, insofar such variations areappropriate to perform in the disclosed invention. It is to beunderstood that the value to which the modifier “about” refers is itselfalso specifically, and preferably, disclosed.

The recitation of numerical ranges by endpoints includes all numbers andfractions subsumed within the respective ranges, as well as the recitedendpoints.

All documents cited in the present specification are hereby incorporatedby reference in their entirety.

Unless otherwise defined, all terms used in disclosing the invention,including technical and scientific terms, have the meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. By means of further guidance, definitions for the terms used inthe description are included to better appreciate the teaching of thepresent invention. The terms or definitions used herein are providedsolely to aid in the understanding of the invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment, but may. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would beapparent to a person skilled in the art from this disclosure, in one ormore embodiments. Furthermore, while some embodiments described hereininclude some but not other features included in other embodiments,combinations of features of different embodiments are meant to be withinthe scope of the invention, and form different embodiments, as would beunderstood by those in the art. For example, in the following claims,any of the claimed embodiments can be used in any combination.

In fabricating dental or oral appliances such as retainers and alignersby using three-dimensional (3D) printing processes, forming theappliances with such methods may be accomplished by utilizing hollowshapes with complex geometries using tiny cells known as latticestructures. Topology optimization can be used to assist in the efficientblending of solid-lattice structures with smooth transitional materialvolume. Lattice performance can be studied under tension, compression,shear, flexion, torsion, and fatigue life.

During the 3D printing process, the formed oral appliance may need to besupported by an intermediate structure given the complex shapes beingconstructed. Such intermediate structures may be used temporarily andthen removed, separated, or otherwise disengaged from the oral appliancebeing formed.

FIG. 1 shows a cross-sectional side view of an exemplary 3D printeddental appliance 10 with a temporary support structure 14 positionedwithin the appliance 10. Typically, the dental appliance 10 is designedto stay in a patient's mouth more than 18 hours a day for about onemonth. Aside from durability, the shell of the dental appliance 10 isdesirably thin typically having a thickness of about 0.5 mm. To be ableto 3D print such a shell or dental portion for covering the teeth ortooth, the structure of FIG. 1 may utilize the inner support structure14 to structurally support or buttress the appliance 10 formed upon thesupport structure 14. Because the occlusal surface 12 of the oralappliance 10 may have a complex anatomy (or terrain), the interfacingsurface 16 of the support structure 14 may be formed to mirror theocclusal surface 12 so that the occlusal surface 12 formed upon theinterfacing surface 16 during the manufacturing process sufficientlysupports the oral appliance 10.

Once formation of the appliance 10 has been completed, the supportstructure 14 may be readily removed from the opening 18 defined by theappliance 10. Hence, in one embodiment, the width of the supportstructure 14 may be similar to the opening 18 of the appliance 10 toallow for removal of the support 14 from the appliance 10. The appliance10 may be fabricated from a number of different types of polymers, e.g.,silicone, polyurethane, polyepoxide, polyamides, or blends thereof,etc., and the support structure 14 may be fabricated from the same,similar, or different material than the appliance 10. Fabricating thesupport structure 14 from a material different than the material of theappliance 10 may facilitate the separation and removal of the supportstructure 14 from the appliance 10 when finished.

Aside from having the support structure 14 positioned directly below theappliance 10 during fabrication, other embodiments may include a supportstructure formed as one or more layers, as shown in the partialcross-sectional side views of FIGS. 2A and 2B. FIG. 2A shows oneembodiment of an oral appliance 20 during fabrication where an innercore layer 22 may be formed (e.g., via 3D printing) of a first materialconfigured and shaped to follow the contours of the dentition. With theinner core layer 22 fabricated, an inner appliance layer 24 may beprinted upon an interior surface of the inner core layer 22 and an outerappliance layer 26 may be printed upon an exterior surface of the innercore layer 22. The inner core layer 22 may thus be formed to be slightlyoversized relative to the dentition to allow for the fabrication of theinner appliance layer 24 to size. The inner appliance layer 24 and outerappliance layer 26 may be printed upon the inner core layer 22 eithersequentially or simultaneously to form the desired oral appliance 20.Subsequently, the inner core layer 22 may be melted, washed, orotherwise dissolved, e.g., via chemicals, leaving the completed oralappliance 20 with inner appliance layer 24 and outer appliance layer 26intact.

In another embodiment, FIG. 2B shows a cross-sectional side view of anarrangement where the oral appliance 28 may be fabricated by anappliance layer 30 formed between an inner core layer 32 and outer corelayer 34. The inner core layer 32 may be formed to be slightlyundersized relative to the dentition to allow for the fabrication of theappliance layer 30 to size. Once the appliance layer 30 has beenfabricated while supported by the inner core layer 32 and outer corelayer 34, both the inner core layer 32 and outer core layer 34 may beremoved or otherwise dissolved leaving the appliance layer 30.

In yet another embodiment, the oral appliance may be fabricated withvarious features such as projections, protrusions, or other shapes forproviding additional flexibility in treating the patient. FIG. 3 shows across-sectional side view of one example of a printed oral appliance 40having a pocket or cavity 42 formed along a side portion of the device,e.g., for receiving an attachment such as an elastic that can be placedupon the pocket or cavity 42. In this example, the support structure caninclude a feature or projection 44 which causes the corresponding pocketor cavity 42 to protrude from the oral appliance 40, as shown. Certainfeatures can be 3D printed for future assembly to provide additionaltreatment options and improve the effectiveness of the oral appliance.In other embodiments, the support structure may be formed without anyadditional features but the feature or projection 44 may be adhered orotherwise secured to selected regions of the support structure forselectively forming the corresponding pocket or cavity 42 upon the oralappliance 40. The feature or projection may be optionally designed,e.g., to enable non-isotropic friction in one direction which helpsdevice to grab teeth better and move to its designed position.

In yet another embodiment, features or projections may instead beincorporated into the oral appliance to impart additional forces or tofacilitate tooth movements. One example is shown in the top view of FIG.4 which illustrates a projection 50 (e.g., a polymeric or metallic ball)positioned by an oral appliance (not shown for clarity purposes) betweentwo adjacent teeth 54, 56. The projection 50 may be fabricated as partof the oral appliance which extends from the appliance and into contactagainst specified regions of a tooth or teeth, e.g., to facilitate aseparation movement between the adjacent teeth 54, 56. While a singleprojection 50 is shown, such a projection or multiple projections may beused within the oral appliance.

Aside from projections, the oral appliance 60 may also define a numberof channels, grooves, or features which support the use of additionaldevices. An exemplary oral appliance 60 is shown in the top view of FIG.5 positioned upon the teeth 62 of a subject and further having slots 64,66 defined within the oral appliance 60 for supporting wires 68 within.The oral appliance 60 may be configured and printed with the slots 64,66 to receive, e.g., wires, hooks, rubber bands, etc., for supplementingthe corrective forces imparted by the oral appliance 60 for correctingmalocclusions as well as to enhance the material strength and preventmaterial relaxation, e.g., in cases of arch expansion. The wire 68 isshow anchored within the slots 64, 66 of oral appliance 60 forillustrative purposes but alternative variations for slot positioning orincorporating other features or elements may also be used.

In another embodiment, due to accurate gingival modeling, the shell ofthe oral appliance can be extended or thickened to cover the gum areaswithout hurting patients. Such extended areas can strengthen the shell,e.g., plastic, especially at times when a shortened plastic shell maynot be able to provide the strength needed.

FIG. 6 shows an exemplary process for adjusting the thickness of the 3Dprinted oral appliance. With the subject's dentition scanned andelectronically converted, the upper and lower arch models 70 may beloaded into the memory of a computer system having a programmableprocessor. The bite registration may be set and the resulting digitalmodel may be mounted on a virtual articulator 72. The system may beprogrammed to generate an initial shell model having a predeterminedthickness 74 where the thicker the portions of the oral applianceprovides a relatively stronger region. The practitioner can incorporatefeatures such as the projections 50 shown above in FIG. 4 and/or furtherincorporate additional features such as slots 64, 66 or any otherfeatures into the model of the oral appliance. The system may beprogrammed to then activate an articulator to perform a simulated bite76 between the upper and lower arch models to calculate any overlapbetween the upper and lower arch shell 78. Any resulting stresses on theshell model of the oral appliance may also be determined.

The system may then remove any overlap by trimming off the shellmaterial 80 in the model and any isolated islands or peninsular piecesmay then be removed as well 82. The resulting 3D model may then beexported to a 3D printer 84 for fabricating the dental appliance orshell.

FIG. 7 shows another exemplary process for determining the thickness ofan oral appliance based on physical simulations. In this process, thedigital model of the lower arch and upper arch may be loaded 90 into thememory of a computer system, as above. The new desired configuration forthe arch and/or dentition may be input into the system which maycalculate the necessary movements to occur for the tooth or teeth 92.The system may then generate an analytical model for an initial shellshape 94. The system may further run an analytical model to optimizeshell shapes, including thicknesses and potential ancillary componentsor parts which may be needed or desired 96. The analytical 3D model maybe further optimized for best patient comfort and resin costminimization 98 and the result may then be provided to a 3D printer 100for fabricating the oral appliance or shell.

Generally, the pressure formed plastic shell forming conventional oralappliances have intrinsic short-comings. Ideally the plastic shell has arelatively thinner layer (e.g., thinner than other regions of theappliance) on regions of the appliance which contact the occlusal areasof the patient's dentition so the patient's bite is unaffected when inuse during treatment. On the other hand, the embrasure or side surfaceareas are ideally relatively thicker to provide enough force to push thetooth or teeth to its designated location for correcting malocclusions.Oftentimes, these embrasure regions are stretched thinner during theforming process for the oral appliance. In forming the oral appliance,the system described herein may determine the areas of the oralappliance which affects the patient's bite and may configure theappliance to be thinner in particular areas or may even remove somematerial from the appliance entirely to form a hole.

Free-form lattice structures which fit at least part of the surface,e.g. external contour, of a body part may be used to form the oralappliance. Specifically, the embodiments described may utilize free-formlattice structures for forming or fabricating appliances which aredesigned for placement or positioning upon the external surfaces of apatient's dentition for correcting one or more malocclusions. Thefree-form structure is at least partially fabricated by additivemanufacturing techniques and utilizes a basic structure comprised of alattice structure. The lattice structure may ensure and/or contribute toa free-form structure having a defined rigidity and the latticestructure may also ensure optimal coverage on the dentition by a coatingmaterial which may be provided on the lattice structure. The latticestructure is at least partly covered by, impregnated in, and/or enclosedby the coating material. Furthermore, embodiments of the latticestructure can contribute to the transparency of the structure.

The term “free-form lattice structure”, as used herein, refers to astructure having an irregular and/or asymmetrical flowing shape orcontour, more particularly fitting at least part of the contour of oneor more body parts. Thus, in particular embodiments, the free-formstructure may be a free-form surface. A free-form surface refers to an(essentially) two-dimensional shape contained in a three-dimensionalgeometric space. Indeed, as detailed herein, such a surface can beconsidered as essentially two-dimensional in that it has limitedthickness, but may nevertheless to some degree have a varying thickness.As it comprises a lattice structure rigidly set to mimic a certain shapeit forms a three-dimensional structure.

Typically, the free-form structure or surface is characterized by a lackof corresponding radial dimensions, unlike regular surfaces such asplanes, cylinders and conic surfaces. Free-form surfaces are known tothe skilled person and widely used in engineering design disciplines.Typically non-uniform rational B-spline (NURBS) mathematics is used todescribe the surface forms; however, there are other methods such asGorden surfaces or Coons surfaces. The form of the free-form surfacesare characterized and defined not in terms of polynomial equations, butby their poles, degree, and number of patches (segments with splinecurves). Free-form surfaces can also be defined as triangulatedsurfaces, where triangles are used to approximate the 3D surfaces.Triangulated surfaces are used in Standard Triangulation Language (STL)files which are known to a person skilled in CAD design. The free-formstructures fit the surface of a body part, as a result of the presenceof a rigid basic structures therein, which provide the structures theirfree-form characteristics.

The term “rigid” when referring to the lattice structure and/orfree-form structures comprising them herein refers to a structureshowing a limited degree of flexibility, more particularly, the rigidityensures that the structure forms and retains a predefined shape in athree-dimensional space prior to, during and after use and that thisoverall shape is mechanically and/or physically resistant to pressureapplied thereto. In particular embodiments the structure is not foldableupon itself without substantially losing its mechanical integrity,either manually or mechanically. Despite the overall rigidity of theshape of the envisaged structures, the specific stiffness of thestructures may be determined by the structure and/or material of thelattice structure. Indeed, it is envisaged that the lattice structuresand/or free-form structures, while maintaining their overall shape in athree-dimensional space, may have some (local) flexibility for handling.As will be detailed herein, (local) variations can be ensued by thenature of the pattern of the lattice structure, the thickness of thelattice structure and the nature of the material. Moreover, where thefree-form structures envisaged herein comprise separate parts (e.g.non-continuous lattice structures) which are interconnected (e.g., byhinges or by areas of coating material), the rigidity of the shape maybe limited to each of the areas comprising a lattice structure.

Descriptions of dental appliance fabrication processes may be found infurther detail in U.S. Prov. App. 62/238,514 filed Oct. 7, 2015, whichis incorporated herein by reference in its entirety and for any purpose.

Generally, the fabrication process includes designing an appliance wornon teeth to be covered by a free-form structure, manufacturing the mold,and providing the (one or more) lattice structures therein and providingthe coating material in the mold so as to form the free-form structure.The free-form structures are patient-specific, i.e. they are made to fitspecifically on the anatomy or dentition of a certain patient, e.g.,animal or human. In fabricating the oral appliance, the 3Drepresentation of the surfaces, e.g. external contours, of a patient'sdentition for correcting one or more malocclusions may be captured via a3D scanner, e.g. a hand-held laser scanner, and the collected data canthen be used to construct a digital, three dimensional model of the bodypart of the subject. Alternatively, the patient-specific images can beprovided by a technician or medical practitioner by scanning the subjector part thereof. Such images can then be used as or converted into athree-dimensional representation of the subject, or part thereof.Additional steps wherein the scanned image is manipulated and forinstance cleaned up may be envisaged.

FIG. 8A shows a perspective view of an exemplary oral appliance 120having two parts 122 (for the upper dentition and lower dentition). Asshown, the oral appliance 120 generally includes a lattice structure 124which can be used in a process for manufacturing the final oralappliance. In the process, the lattice structure 124 may first be 3Dprinted in a shape which approximates the oral appliance to befabricated for correcting the malocclusion and the lattice structure maybe positioned within a dental appliance 126, 126′. Then, the dentalappliance 126, 126′ containing the formed lattice structure 124 may befilled with the impregnating material 128, e.g., polymer or othermaterials described herein. After setting of the impregnating material128, the dental appliance halves 126, 126′ are removed to yield thecoated oral appliance 120.

While the entire lattice structure 124 may be coated or impregnated bythe impregnating material 128, only portions of the lattice structure124 may be coated or particular surfaces of the lattice structure 124may be coated while leaving other portions exposed. Variations of theseembodiments are described in further detail below with respect to theoral appliance 120 shown in FIG. 8A.

As can be appreciated, an approach to 3D printed progressive aligners ofvarying and/or increasing thickness has certain advantages. For example,the rate of incremental increase in thickness may not be dependent onstandard thicknesses of sheet plastic available as an industrialcommodity. An optimal thickness could be established for the 3D printingprocess. For example, rather than being limited to the, e.g., 0.040,0.060 and 0.080 in. thickness sequence, a practitioner such as anorthodontist could choose a sequence such as, e.g., 0.040, 0.053 and0.066 in. thickness, for an adult patient whose teeth are known toreposition more slowly compared to a rapidly growing adolescent patient.

Given the concept that an aligner formed from thinner material generatesgenerally lower corrective forces than an identically configured alignerformed from thicker material, it follows that an aligner could be 3Dprinted so as to be thicker in areas where higher forces are needed andthinner in areas where lighter forces are needed. Having the latitude toproduce aligners with first a default thickness and then areas ofvariable thickness could be favorably exploited to help practitionersaddress many difficult day-to-day challenges. For example, anymalocclusion will consist of teeth that are further from their desiredfinished positions than other teeth. Further, some teeth are smallerthan others and the size of the tooth corresponds to the absolute forcethreshold needed to initiate tooth movement. Other teeth may seem to bemore stubborn due to many factors including the proximity of the tooth'sroot to the boundaries between cortical and alveolar bony support. Stillother teeth are simply harder to correctively rotate, angulate, orup-right than others. Still other teeth and groups of teeth may need tobe bodily moved as rapidly as possible over comparatively large spans toclose open spaces. For at least such reasons, the option of tailoringaligner thickness and thus force levels around regions containing largerteeth or teeth that are further from their desired destinations, orthose stubborn teeth allows those selected teeth to receive higherforces than small, nearly ideally positioned teeth.

The free-form lattice structure for the dental appliances can be atleast partially fabricated by additive manufacturing (AM). Moreparticularly, at least the basic structure may be fabricated by additivemanufacturing using the lattice structure. Generally, AM can may includea group of techniques used to fabricate a tangible model of an objecttypically using 3D computer aided design (CAD) data of the object. Amultitude of AM techniques are available for use, e.g.,stereolithography, selective laser sintering, fused deposition modeling,foil-based techniques, etc. Selective laser sintering uses a high powerlaser or another focused heat source to sinter or weld small particlesof plastic, metal, or ceramic powders into a mass representing the 3Dobject to be formed. Fused deposition modeling and related techniquesmake use of a temporary transition from a solid material to a liquidstate, usually due to heating. The material is driven through anextrusion nozzle in a controlled way and deposited in the required placeas described among others in U.S. Pat. No. 5,141,680, which isincorporated herein by reference in its entirety and for any purpose.Foil-based techniques fix coats to one another by use of, e.g., gluingor photo polymerization or other techniques, and then cuts the objectfrom these coats or polymerize the object. Such a technique is describedin U.S. Pat. No. 5,192,539, which is incorporated herein by reference inits entirety and for any purpose.

Typically AM techniques start from a digital representation of the 3Dobject to be formed. Generally, the digital representation is slicedinto a series of cross-sectional layers which can be overlaid to formthe object as a whole. The AM apparatus uses this data for building theobject on a layer-by-layer basis. The cross-sectional data representingthe layer data of the 3D object may be generated using a computer systemand computer aided design and manufacturing (CAD/CAM) software.

The basic structure comprising the lattice structure may thus be made ofany material which is compatible with additive manufacturing and whichis able to provide a sufficient stiffness to the rigid shape of theregions comprising the lattice structure in the free-form structure orthe free-form structure as a whole. Suitable materials include, but arenot limited to, e.g., polyurethane, acrylonitrile butadiene styrene(ABS), polycarbonate (PC), PC-ABS, polyamide, polyamide with additivessuch as glass or metal particles, methylmethacrylate-acrylonitrile-butadiene-styrene copolymer, etc.

The lattice structure itself may be comprised of a rigid structure whichhas an open framework of, e.g., 3D printed lattices. Lattice structuresmay contain a plurality of lattices cells, e.g., dozens, thousands,hundreds of thousands, etc. lattice cells. Once the 3D model of thedentition is provided, the process may generate STL files to print thelattice version of the 3D model and create support structures wherenecessary. The system identifies where material is needed in anappliance and where it is not required, prior to placing and optimizingthe lattice.

The system may optimize dental lattices in two phases. First, it appliesa topology optimization allowing more porous materials with intermediatedensities to exist. Second, the porous zones are transformed intoexplicit lattice structures with varying material volume. In the secondphase, the dimensions of the lattice cells are optimized. The result isa structure with solid parts plus lattice zones with varying volumes ofmaterial. The system balances the relationship between material densityand part performance, for example, with respect to the stiffness tovolume ratio, that can impact design choices made early in the productdevelopment process. Porosity may be especially important as afunctional requirement for biomedical implants. Lattice zones could beimportant to the successful development of products where more than merestiffness is required. The system can consider buckling behavior,thermal performance, dynamic characteristics, and other aspects, all ofwhich can be optimized. The user may manipulate material density basedupon the result of an optimization process, comparing stronger versusweaker, or solid versus void versus lattice, designs. The designer firstdefines the objective, then performs optimization analysis to inform thedesign.

While 3D printing may be used, the lattices can also be made of strips,bars, girders, beams or the like, which are contacting, crossing oroverlapping in a regular pattern. The strips, bars, girders, beams orthe like may have a straight shape, but may also have a curved shape.The lattice is not necessarily made of longitudinal beams or the like,and may for example consist of interconnected spheres, pyramids, etc.among others.

The lattice structure is typically a framework which contains a regular,repeating pattern as shown in FIG. 8A, wherein the pattern can bedefined by a certain unit cell. A unit cell is the simplest repeat unitof the pattern. Thus, the lattice structure 124 is defined by aplurality of unit cells. The unit cell shape may depend on the requiredstiffness and can for example be triclinic, monoclinic, orthorhombic,tetragonal, rhombohedral, hexagonal or cubic. Typically, the unit cellsof the lattice structures have a volume ranging from, e.g., 1 to 8000mm³, or preferably from 8 to 3375 mm³, or more preferably from 64 to3375 mm³, or most preferably from 64 to 1728 mm³. The unit cell size maydetermine, along with other factors such as material choice and unitcell geometry, the rigidity (stiffness) and transparency of thefree-form structure. Larger unit cells generally decrease rigidity andincrease transparency, while smaller unit cells typically increaserigidity and decrease transparency. Local variations in the unit cellgeometry and/or unit cell size may occur, in order to provide regionswith a certain stiffness. Therefore, the lattice 124 may comprise one ormore repeated unit cells and one or more unique unit cells. In order toensure the stability of the lattice structure 124, the strips, bars,girders, beams or the like may have a thickness or diameter of, e.g.,0.1 mm or more. In particular embodiments, the strips, bars, girders,beams or the like may preferably have a thickness or diameter of, e.g.,0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 5 mm or more.The main function of the lattice structure 124 is to ensure a certainstiffness of the free-form structure. The lattice structure 124 mayfurther enhance or ensure transparency, as it is an open framework. Thelattice structure 124 can preferably be considered as a reticulatedstructure having the form and/or appearance of, e.g., a net or grid,although other embodiments may be used.

The stiffness of the lattice structure depends on factors such as thestructure density, which depends on the unit cell geometry, the unitcell dimensions and the dimensions of the strips, bars, girders, beams,etc. of the framework 132. Another factor is the distance, S, betweenthe strips and the like, or in other words, the dimensions of theopenings in the lattice structure, as shown in the detail exemplary viewof FIG. 8B. Indeed, the lattice structure is an open framework andtherefore comprises openings 134. In particular embodiments, the openingsize S of the lattice structure is between, e.g., 1 and 20 mm, between 2and 15 mm, or between 4 and 15 mm. In preferred embodiments, the openingsize is between, e.g., 4 and 12 mm. The size of the openings may be theequal to or smaller than the size of the unit cell 134 while in otherembodiments, the openings may be uniform in size or arbitrary in size.In yet another alternative, differing regions of the lattice may haveopenings which are uniform in size but which are different from otherregions.

In particular embodiments, the free-form structures may comprise alattice structure having one or more interconnected reticulated layers,as shown in the exemplary end view of FIG. 8C. For instance, the latticestructure may comprise one, two, three or more reticulated layers 138,where the structure comprises different at least partially superimposedand/or interconnected layers 136, 136′, 136″ within the latticestructure. The degree of stiffness provided by the lattice structure mayincrease with the number of reticulated layers provided therein. Infurther particular embodiments, the free-form structures may comprisemore than one lattice structure. The examples shown are merelyillustrative of the different embodiments.

For certain applications the lattice structure may further comprise oneor more holes with a larger size than the openings or unit cells asdescribed hereinabove. Additionally or alternatively, the latticestructure may not extend over the entire shape of the free-formstructure such that openings in the structure or regions for handling,e.g., tabs or ridges, and/or regions of unsupported coating material areformed. An example of such an application is a facial mask, where holesare provided at the location of the eyes, mouth and/or nose holes.Typically, these latter holes are also not filled by the coatingmaterial.

Similarly, in particular embodiments, the size of the openings which areimpregnated in and/or enclosed by the adjoining material may rangebetween, e.g., 1 and 20 mm. The holes in the lattice structure(corresponding to holes in the free-form structure) as described hereinwill also typically have a size which is larger than the unit cell.Accordingly, in particular embodiments, the unit cell size rangesbetween, e.g., 1 and 20 mm.

According to particular embodiments, as shown in the end view of FIG.8D, the envisaged free-form structure may contain regions 133 comprisedonly of the coating material 131. This may be of interest in areas whereextreme flexibility of the free-form structure is desired.

In particular embodiments, the envisaged free-form structure maycomprise a basic structure which contains, in addition to a latticestructure, one or more limited regions which do not contain a latticestructure, but are uniform surfaces, as shown in the detail perspectiveview of FIG. 8E. Typically these form extensions 135 from the latticestructure with a symmetrical shape (e.g. rectangular, semi-circle,etc.). Such regions, however, typically encompass less than, e.g., 50%,or more particularly less than, e.g., 30%, or most particularly lessthan, e.g., 20% of the complete basic structure. Typically they are usedas areas for handling (manual tabs) of the structure and/or forplacement of attachment structures (clips, elastic string, etc.). Inparticular embodiments, the basic structure may be comprised essentiallyof only a lattice structure.

It can be advantageous for the dental appliance structure to havecertain regions with a different stiffness (such as in the molar teethto provide added force). This can be achieved by providing a latticestructure with locally varying unit cell geometries, varying unit celldimensions and/or varying densities and/or varying thicknesses of thelattice structure (by increasing the number of reticulated layers), asshown in the exemplary detail perspective view of FIG. 8F. Accordingly,in particular embodiments, the lattice structure is provided withvarying unit cell geometries, varying unit cell dimensions, varyinglattice structure thicknesses and/or varying densities 137, 139.Additionally or alternatively, as described herein, the thickness of thecoating material may also be varied, as shown in FIG. 8G. Thus, inparticular embodiments, the free-form structure has a varying thicknesswith a region of first thickness 141 and a region of second thickness143. In further particular embodiments, the free-form structures mayhave regions with a different stiffness, while they retain the samevolume and external dimensions.

In particular embodiments of the free-form structures, the basicstructure or the lattice structure can be covered in part with a coatingmaterial which is different from the material used for manufacturing thelattice structure. In particular embodiments the lattice structure is atleast partly embedded within or enclosed by (and optionally impregnatedwith) the coating material, as shown in the exemplary detail end view ofFIG. 8H. In further embodiments, the coating material is provided ontoone or both surfaces of the lattice structure 136. In particularembodiments only certain surface regions of the basic structure and/orthe lattice structure in the free-form structure are provided with acoating material while portions may be exposed 145. In particularembodiments, at least one surface of the basic structure and/or latticestructure may be coated 131 for at least 50%, more particularly at least80%. In further embodiments, all regions of the basic structure having alattice structure are fully coated, on at least one side, with thecoating material. In further particular embodiments, the basic structureis completely embedded with the coating material, with the exceptions ofthe tabs provided for handling.

In further embodiments, the free-form structure comprises, in additionto a coated lattice structure, regions of coating material not supportedby a basic structure and/or a lattice structure.

Accordingly, in particular embodiments, the free-form structure maycomprise at least two materials with different texture or composition.In other embodiments, the free-form structure may comprise a compositestructure, e.g., a structure which is made up of at least two distinctcompositions and/or materials.

The coating material(s) may be a polymeric material, a ceramic materialand/or a metal. In particular embodiments, the coating material(s) is apolymeric material. Suitable polymers include, but are not limited to,silicones, a natural or synthetic rubber or latex, polyvinylchloride,polyethylene, polypropylene, polyurethanes, polystyrene, polyamides,polyesters, polyepoxides, aramides, polyethyleneterephthalate,polymethylmethacrylate, ethylene vinyl acetate or blends thereof. Inparticular embodiments, the polymeric material comprises silicone,polyurethane, polyepoxide, polyamides, or blends thereof.

In particular embodiments the free-form structures comprise more thanone coating material or combinations of different coating materials.

In specific embodiments, the coating material is a silicone. Siliconesare typically inert, which facilitates cleaning of the free-formstructure.

In particular embodiments, the coating material is an opticallytransparent polymeric material. The term “optically transparent” as usedherein means that a layer of this material with a thickness of 5 mm canbe seen through based upon unaided, visual inspection. Preferably, sucha layer has the property of transmitting at least 70% of the incidentvisible light (electromagnetic radiation with a wavelength between 400and 760 nm) without diffusing it. The transmission of visible light, andtherefore the transparency, can be measured using a UV-VisSpectrophotometer as known to the person skilled in the art. Transparentmaterials are especially useful when the free-form structure is used forwound treatment (see further). The polymers may be derived from one typeof monomer, oligomer or prepolymer and optionally other additives, ormay be derived from a mixture of monomers, oligomers, prepolymers andoptionally other additives. The optional additives may comprise ablowing agent and/or one or more compounds capable of generating ablowing agent. Blowing agents are typically used for the production of afoam.

Accordingly, in particular embodiments, the coating material(s) arepresent in the free-form structure in the form of a foam, preferably afoamed solid. Thus, in particular embodiments, the lattice structure iscoated with a foamed solid. Foamed materials have certain advantagesover solid materials: foamed materials have a lower density, requireless material, and have better insulating properties than solidmaterials. Foamed solids are also excellent impact energy absorbingmaterials and are therefore especially useful for the manufacture offree-form structures which are protective elements (see further). Thefoamed solid may comprise a polymeric material, a ceramic material or ametal. Preferably, the foamed solid comprises one or more polymericmaterials.

The foams may be open cell structured foams (also known as reticulatedfoams) or closed cell foams. Open cell structured foams contain poresthat are connected to each other and form an interconnected networkwhich is relatively soft. Closed cell foams do not have interconnectedpores and are generally denser and stronger than open cell structuredfoams. In particular embodiments, the foam is an “integral skin foam”,also known as “self-skin foam”, e.g., a type of foam with a high-densityskin and a low-density core.

Thus in particular embodiments, free-form structures may comprise abasic structure which includes a lattice structure which is at leastpartially coated by a polymeric or other material as described herein.For some applications, the thickness of the coating layer and theuniformity of the layer thickness of the coating are not essential.However, for certain applications, it can be useful to provide a layerof coating material with an adjusted layer thickness in one or morelocations of the free-form structure, for example, to increase theflexibility of the fit of the free-form structure on the body part.

The basic structure of the freeform structures envisaged herein can bemade as a single rigid free-form part which does not need a separateliner or other elements. Independent thereof it is envisaged that thefree-form structures can be further provided with additional components147 such as sensors, straps, or other features for maintaining thestructure in position on the body, or any other feature that may be ofinterest in the context of the use of the structures and integratedwithin or along the structure, as shown in FIG. 8I. Various examples ofsensors which may be integrated are described in further detail herein.

In certain embodiments, the free-form structure comprises a single rigidlattice structure (optionally comprising different interconnected layersof reticulated material). However, such structures often only allow alimited flexibility, which may cause discomfort to a person or animalwearing the free-form structure. An increase in flexibility can beobtained if the free-form structure comprises two or more separate rigidlattice structures which can move relative to each other. These two ormore lattice structures are then enclosed by a material as describedabove, such that the resulting free-form structure still is made orprovided as a single part. The rigidity of the shape of the free-formstructure is ensured locally by each of the lattice structures, whileadditional flexibility during placement is ensured by the fact thatthere is a (limited) movement of the lattice structures relative to eachother. Indeed, in these embodiments, the coating material and/or a morelimited lattice structure) will typically ensure that the latticestructures remain attached to each other.

In particular embodiments, the lattice structures are partially orcompletely overlapping. However, in particular embodiments, thedifferent lattice structures are non-overlapping. In further particularembodiments, the lattice structures are movably connected to each other,for example via a hinge or other movable mechanism 149, 149′, as shownin the detail end view of FIG. 8J. In particular embodiments theconnection is ensured by lattice material. In further particularembodiments the lattice structures may be interconnected by one or morebeams which form extensions of the lattice structures. In furtherembodiments the lattice structures are held together in the free-formstructure by the coating material. An example of such a free-formstructure is a facial mask with a jaw structure that is movable withrespect to the rest of the mask. Accordingly, in particular embodiments,the lattice structure comprises at least two separate lattice structuresmovably connected to each other, whereby the lattice structures areintegrated into the free-form structure, as shown.

The free-form structure may be used for wound treatment as describedherein. For optimal healing, the free-form structure provides a uniformcontact and/or pressure on the wound site or specific locations of thewound site. The lattice structure makes it simple to incorporatepressure sensors into the free-form structure according to the presentinvention. The sensors can be external sensors, but may also be internalsensors. Indeed, the lattice structure can be designed such that itallows mounting various sensors at precise locations, as describedabove, before impregnating and/or enclosing the lattice structure by apolymer or other material.

Additionally or alternatively, the free-form structure may comprise oneor more other sensors, as described above in FIG. 8I, such as atemperature sensor, a moisture sensor, an optical sensor, a straingauge, an accelerometer, a gyroscope, a GPS sensor, a step counter, etc.Accelerometers, gyroscopes, GPS sensors and/or step counter may forexample be used as an activity monitor. Temperature sensor(s), moisturesensor(s), strain gauge(s) and/or optical sensor(s) may be used tomonitor the healing process during wound treatment. Specifically, theoptical sensor(s) may be used to determine collagen fiber structure asexplained in US Pat. App. 2011/0015591, which is hereby incorporated byreference in its entirety and for any purpose.

Accordingly, in particular embodiments the free-form structure furthercomprises one or more external and/or internal sensors. In specificembodiments, the free-form structure comprises one or more internalsensors. In certain embodiments, the free-form structure comprises oneor more pressure and/or temperature sensors.

The skilled person will understand that in addition to the sensor(s),also associated power sources and/or means for transmitting signals fromthe sensor(s) to a receiving device may be incorporated into thefree-form structure, such as wiring, radio transmitters, infraredtransmitters, and the like.

In particular embodiments, at least one sensor may comprisemicro-electronic mechanical systems (MEMS) technology, e.g., technologywhich integrates mechanical systems and micro-electronics. Sensors basedon MEMS technology are also referred to as MEMS-sensors and such sensorsare small and light, and consume relatively little power. Non-limitingexamples of suitable MEMS-sensors are the STTS751 temperature sensor andthe LIS302DL accelerometer STMicroelectronics.

As shown in FIG. 8K, the lattice structure also allows providing thefree-form structure with one or more (internal) channels 151. Thesechannels may be used for the delivery of treatment agents to theunderlying skin, tissue, or teeth. The channels may also be used for thecirculation of fluids, such as heating or cooling fluids.

One philosophy of orthodontic treatment is known as “Differential Force”called out for the corrective forces directed to teeth to be closelytailored according to the ideal force level requirements of each tooth.The Differential Force approach was supported by hardware based oncalibrated springs intended to provide only those ideal force levelsrequired. Carrying the concepts of the Differential Force approachforward to the precepts of aligner fabrication, one can appreciate thatCNC-machined aligners exhibiting carefully controlled variable thicknesscan accomplish the Differential Force objectives on a tooth-by-toothbasis. The compartments surrounding teeth can have wall thicknessesestablished at the CAD/CAM level by a technician based on the needs ofeach tooth. A 3D printed aligner can have a limitless series of regions,each with a unique offset thickness between its inner and outersurfaces.

Prior to installing such devices, a practitioner may assess the progressof a case at mid-treatment for example and in particular, make note ofproblem areas where the desired tooth response is lagging or instanceswhere particular teeth are stubbornly not moving in response totreatment forces. The 3D printed structure can include a group of smalldevices that are intended to be strategically positioned and 3D printedwith an aligner's structure. Such devices are termed “alignerauxiliaries.” FIG. 9 is a detail view of a portion of an aligner 140showing a 3D printed area 142 that is machined allowing thicker materialto accept an elastic 144. Other 3D printed geometries of interest wouldbe divots or pressure points, creating openings/windows on the alignerfor a combination treatment, e.g., forming hooks on the aligner forelastic bands, among others. Aligner auxiliaries may be installed inthose locations to amplify and focus corrective forces of the aligner toenhance correction. For example, an auxiliary known as a tack can beinstalled after a hole of a predetermined diameter is pierced through awall of a tooth-containing compartment of an aligner. The diameter ofthe hole may be slightly less than the diameter of a shank portion ofthe tack which may be printed directly on the aligner. Suchprogressively-sized tacks and other auxiliary devices are commerciallyavailable to orthodontists who use them to augment and extend the toothposition correcting forces of aligners.

Bumps can also be used and serve to focus energy stored locally in theregion of the aligner's structure adjacent to a bump. Theinward-projecting bump causes an outward flexing of the aligner materialin a region away from the tooth surface. Configured in this way, bumpsgather stored energy from a wider area and impinge that energy onto thetooth at the most mechanically advantageous point, thus focusingcorrective forces most efficiently. An elastic hook feature 150 can be3D printed directly in an otherwise featureless area of an aligner'sstructure, as shown in the side views of FIGS. 10A and 10B. Elastichooks may also be used as anchor points for orthodontic elastics thatprovide tractive forces between sectioned portions of an aligner (or analigner and other structures fixedly attached to the teeth) as neededduring treatment.

Aside from hook features 150, other features such as suction features152 may be fabricated for adherence to one or more particular teeth T,as shown in the partial cross-sectional view of FIG. 10C. In thismanner, the aligner may exert a directed force 154 concentrated on theone or more particular teeth.

In yet another embodiment, as shown in the perspective view of FIG. 10D,the occlusal surfaces of the aligner may be fabricated to have areasdefined to facilitate eating or talking by the patient. Such featuresmay include occlusal regions which are thinned, made into flattenedsurfaces 156, or made with any number of projections 158 to facilitateeating.

Additionally, different portions of the aligners may be fabricated tohave different areas 160 of varying friction, as shown in theperspective view of FIG. 10E. Such varying areas may be formed, e.g.,along the edges to prevent tearing of the aligner material.

Additional attachments can be formed on the 3D printed dental appliancessuch as particulate coatings. The particulate coating 162 may be formedon the tooth engaging surface of the lattice 3D printed appliance in anyconvenient manner, e.g., fusion, sintering, etc., as shown in theperspective view of FIG. 10F. The particles making up the coating may beany convenient shape, including a spherical shape or an irregular shape,and may be constructed of metal (including alloys), ceramic, polymer, ora mixture of materials. The particulate coating adhered to the toothengaging surface may take the form of discrete particles which arespaced apart from each other on the surface, or the form of a layer ormultiple layers of particles bonded together to produce a network ofinterconnected pores. The particulate coating provides a porousinterface into which a fluid bonding resin may readily flow andpenetrate. Upon curing of the resin to solid form, mechanical interlockis achieved between the cured resin and the particulate coating. Undersome circumstances chemical bonding in addition to this mechanicalbonding may be achieved, e.g., by the use of polycarboxylate or glassionomer cements with stainless steel and other metallic substrates andwith ceramic substrates.

For a coating of integrally-joined particles which make up a porousstructure having a plurality of interconnected pores extendingtherethrough, the particles are usually about −100 mesh and preferably amixture of particles of varying particle sizes restricted to one ofthree size ranges, e.g., −100+325 mesh (about 50 to about 200 microns),−325+500 mesh (about 20 to about 50 microns), and −500 mesh (less thanabout 20 microns). The size of the particles in the porous structuredetermines the pore size of the pores between the particles.Smaller-sized pores are preferred for fluid resin bonding agents whereaslarger-sized pores are preferred for more viscous cementitious bondingmaterials. The selection of particle size is also used to control theporosity of the coating to within the range of about 10 to about 50% byvolume.

An adequate structural strength is required for the composite ofsubstrate and coating, so that any fracture of the joint of the bracketto the tooth occurs in the resin and not in the coating. To achieve thiscondition, the structural strength of the coating, the interface betweenthe coating and the substrate and the substrate itself is at least 8MPa.

The applications of the devices and methods discussed above are notlimited to the dental applications but may include any number of furthertreatment applications. Moreover, such devices and methods may beapplied to other treatment sites within the body. Modification of theabove-described assemblies and methods for carrying out the invention,combinations between different variations as practicable, and variationsof aspects of the invention that are obvious to those of skill in theart are intended to be within the scope of the claims.

What is claimed is:
 1. An oral appliance assembly, comprising: a supportstructure having a width and an interfacing surface which corresponds toan outer occlusal surface of a dentition of a subject, wherein thesupport structure is fabricated from a first material; an oral applianceformed upon the exterior surface of the support structure via threedimensional printing such that an interior of the formed oral applianceconforms to the dentition of the subject and where the oral appliancefurther defines an opening which is similar to the width of the supportstructure such that the width of the support structure is removablethrough the opening from the interior of the formed oral appliance,wherein the oral appliance is fabricated from a second materialdifferent from the first material.
 2. The assembly of claim 1 whereinthe second material forming the oral appliance comprises a plastic,polymer, ceramic, or metal.
 3. The assembly of claim 2 wherein thepolymer comprises silicone, polyurethane, polyepoxide, polyamides, orblends thereof.
 4. The assembly of claim 1 further comprising aplurality of oral appliances each formed in a sequence configured tomove one or more teeth of the subject to correct for malocclusions. 5.The assembly of claim 1 wherein the oral appliance comprises one or moredental attachments formed upon the oral appliance.
 6. The assembly ofclaim 1 wherein the oral appliance comprises a pocket or cavity definedalong the oral appliance.
 7. The assembly of claim 6 wherein the pocketor cavity defines a surface configured to present non-isotropic frictionin one direction to facilitate adherence with a tooth or teeth.
 8. Theassembly of claim 1 further comprising a projection defined to extendwithin the oral appliance such that the projection is positioned betweentwo adjacent teeth to enable a separation movement.
 9. The assembly ofclaim 1 wherein the oral appliance comprises one or more portions havinga thickness which is relatively thicker configured to strengthen the oneor more portions.
 10. The assembly of claim 1 wherein the oral appliancecomprises one or more portions of the oral appliance configured toextend and cover an area of the subject's gums.
 11. The assembly ofclaim 1 wherein the oral appliance comprises one or more portions havinga thickness which is relatively thinner configured to contact anocclusal area of the dentition.
 12. The assembly of claim 1 wherein theoral appliance comprises one or more portions which define voids in oneor more outer layers of the oral appliance.
 13. The assembly of claim 1wherein the oral appliance further comprises a lattice structure for theoral appliance that minimizes additive manufacturing material usage. 14.The assembly of claim 13 wherein the lattice structure has varying unitcell geometries.
 15. The assembly of claim 1 wherein the oral appliancefurther comprises a clear polymer impregnating or covering at least partof the oral appliance.